Instructional technologists have recently been called upon to examine the assumptions they hold about teaching and learning, and to consider how those assumptions can affect their practice of the discipline. This thesis is an examination of how the assumptions instructional technologists hold can result in instructional materials that do not accomplish the original goals the developers set out to achieve. I explored this issue by examining the case study of programmed instruction, an educational movement from the mid-20th century that promised to revolutionize education but never lived up to its potential. Programmed instruction was heavily influenced by the assumptions of behavioral psychology, such as determinism (human behavior is controlled by scientific law), materialism (the only real world is the physical world), and empiricism (individuals can know the world around them only through the natural senses). It was also influenced by the assumptions of social efficiency (society must actively find the most efficient solutions to social problems) and technological determinism (technology is the most important force in causing social change). These assumptions manifested themselves in a variety of ways in the programmed instruction movement, including a redefinition of all learning problems into the terms of behavioral psychology, an over-reliance on standardized processes of instruction, and a belief that technology alone could solve educational problems. The ways in which programmed instruction manifested itself resulted in the movement prescribing a very rigid and inflexible method of instruction. Because of its inflexibility, programmed instruction quickly fell out of favor with educators and the public. Some modern applications of instructional technology, such as online learning, seem to rely on the same assumptions as programmed instruction did. I conclude this thesis with a discussion of how understanding the assumptions of programmed instruction, and how they led to the movement’s rigidity, can help modern instructional technologists develop online learning materials that are more flexible and able to meet the needs of the students for which they are intended.